CHAPTER 7 SYSTEM DESIGN Expected Outcomes Able to know database design Able to understand designing form and report Able to know designing interfaces
System Design A process of transforming from logical design into physical phase. It is a transition from what is into what should be.
Database Design Database a set of information held in a computer Oxford English Dictionary Database design is the process of developing a detailed data model of a database The data model has all the needed logical and physical design, and physical storage. Logical database- describes data using notation that corresponds to a data organization used by a database management system, using relational database model
Database Design Physical database - Prescribe the technical specifications for computer files and databases in which to store the data.
Database Design Process Logical database modelling and design has four steps: 1.Normalization concepts been use to develop a logical data model 2.Combine normalized data requirements from all user interfaces into one consolidated logical database model
Database Design Process 3.Transform the conceptual E-R data model of the system into normalized data requirements. 4. Compare the consolidated logical database design with the E-R model then generate final logical database model for the system.
Example E-R Diagram Offers Department Course Includes Module Teaches Lecturer Takes Enrols In Student Each module is taught by a lecturer
Physical Database Design Based on logical database model choose a storage format. Grouping attributes from the logical database model into physical records. Arranging related records in secondary memory (hard disks and magnetic tapes) so that records can be stored, retrieved and updated rapidly. Selecting media and structures for storing data to make access more efficient.
Relational Database Model Introduced bye.f. Codd Relational database model concerned with three issues: Data structure (how data is represented) Data integrity (allowable data) Data manipulation (what can be done with the data)
Relational Database Model Relation: has a named, two-dimensional table of data. Each relation consists of a set of named columns and an arbitrary number of unnamed rows
Normalization Normalization is a steps of transforming complex data structures into simple and stable data structures. The output of normalization is that every nonprimary key attribute depends upon the whole primary key.
Form and Report Design Form is a business document that contains some predefined data and may include some areas where additional data are to be filled in. Report is a business document that contains only predefined data. It is a document used solely for reading or viewing data.
Form and Report Characteristics User mental capability, experience, skill, motivation, education, etc. Task time pressure, cost of errors, etc. Environment Social issues and environmental concerns, (norms, interruptions, etc.) System Hardware, platform, OS, devices, etc.
General Design Rules Meaningful Titles title must be clear and specific, version information, and current date when we generate the form and report. Balanced Layout - information should be balanced on the screen, adequate spacing and margins, and clear labels
Color differences Size differences Underlining Capital letter Blinking and audible Intensity differences Highlighting Methods
Using Color Advantages: Soothes or strikes the eye Highlights the important information Attention to warning etc. Disadvantages: Colour pairing may cause problem to colour blindness Resolution may degrade etc
Displaying Text Case - display text in mixed uppercase and lowercase Spacing - use double spacing if possible. Justification - left justify Hyphenation - do not hyphenate words between lines. Abbreviations -use for widely understood
Table and List Rules Use meaningful labels Formatting columns, rows and text Formatting numeric, textual and alphanumeric data
Table and Graph Table is used to read individual data value Graph is used when : Quick summary of information is needed. Tracking trends over time. Forecasting activities.
Usability of Forms and Reports Consistency Efficiency Ease Format Flexibility
Designing Interfaces and Dialogues The process of designing interfaces and dialogues is a user-focused activity. To design usable interfaces and dialogues, designer must ask who, what, when, and how questions used to guide during this process.
Interaction Methods All human-computer interfaces must have an interaction methods style: Command Language Interaction User enter explicit statements into system to invoke operations. Menu Interaction list of system options is provided Drop-down Menu menus open by dropping down onto the display
Interaction Methods Form Interaction Data fields are formatted as similar to paper-based form Object-based Interaction Symbols are used to represent commands or function
Interaction Methods Form Interaction Data fields are formatted as similar to paper-based form Object-based Interaction Symbols are used to represent commands or function Natural Language Interaction Inputs are in a conventional language
Keyboard Mouse Joystick Trackball Touch Screen Light Pen Graphics Tablet Voice Interaction Devices
Designing Interface Designing Layouts: Header information Sequence and time related instruction and formatting Body or data detail Totals or data summary Authorization Comments
Structuring Data Entry: Entry Defaults Units Captioning Format Help Designing Interface
Designing Interface Controlling Data Input: Proper data type Combinations Expected values Range Self-checking digit Values
Designing Interface Providing Feedback: Status information Prompting cues Errors and warning message
Designing Interface Providing Help: Provide extensive system help
Designing Dialogues A dialogue is the sequence in which information is displayed to and obtained from user. Design dialogue sequence Build prototype Assess usability
Designing Dialogue First must gain an understanding of how the users might interact with the system. Therefore designer must have clear understanding of user, task, technological, and environmental characteristics. Formal method to representing dialogues is using dialogue diagram.
Designing Dialogue Second step is a designer building dialogue prototype. They might use several available tools. Last step is all dialogues must be assess their usability.
Questions 1.The following are TRUE about user interface except: a. It was a part of system used by user to retrieve and execute the system function b. It not shows the functions that have in the system c. It consider as the sum of overall result for design d. It was a medium, which allow the interaction between the user and the system.
Questions 2. The sharing of data means that data need to be stored only once [ T/F ] 3. An option button or radio button on a graphical user interface is used for mutually exclusive choices. [ T/F ] 4.What is the difference of data capture, data entry and data processing?
References J.A Hoffer, J.F. George, and J.S. Valacich, "Modern Systems Analysis and Design", 7/E, Addison-Wesley, 2014 Kenneth E. Kendall, Julie E. Kendall., Systems Analysis and Design, Pearson, 2014 C.J. Date, An Introduction to Database Systems,8/E,Pearson, 2003